<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="author" content="wangbo">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box {
      /* 一般看不到before伪元素，故溢出设置隐藏 */
      overflow: hidden;
      width: 200px;
      height: 200px;
      border: 1px solid pink;
      margin: 0 auto;
    }

    .box::before {
      display: block;
      line-height: 200px;
      text-align: center;
      content: '青芒';
      width: 100%;
      height: 100%;
      background-color: hotpink;
      transform: rotate(-180deg);
      transform-origin: left bottom;
      transition: all .5s;
    }

    /* 鼠标经过div 里面的before复原 */
    .box:hover::before {
      transform: rotate(0);
    }

    .bar {
      width: 150px;
      height: 15px;
      border: 1px solid red;
      border-radius: 7px;
      padding: 1px;
    }

    .bar_in {
      width: 50%;
      height: 100%;
      background-color: red;
      transition: width 1s;
    }

    .bar:hover .bar_in {
      width: 100%;
    }

    ul li {
      float: left;
      width: 30px;
      height: 30px;
      border: 1px solid pink;
      margin: 10px;
      text-align: center;
      line-height: 30px;
      list-style: none;
      border-radius: 50%;
      cursor: pointer;
      transition: all .3s;
    }

    ul li:hover {
      transform: scale(1.3);
    }
  </style>
</head>

<body>
  <div class="box"></div>

  <div class="bar">
    <div class="bar_in"></div>
  </div>
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
    <li>6</li>
    <li>7</li>
  </ul>

</body>

</html>